I agree - after freshman year, don't worry about whether the students have prior experience in a language or not. My first experience with Java was in a Databas

I agree - after freshman year, don't worry about whether the students have prior experience in a language or not. My first experience with Java was in a Database class: The teacher gave us a project, said "use Java". She linked to the Java tutorial, and I learned enough for the project in a day or two. I learned Perl the same way (for a bioinformatics course) Of course, if they had been languages in a different paradigm, (e.g., Scheme, Prolog) it may have taken me a bit more time to get going. Still, no reason to not use these languages. Any computer science student should be able to learn a new language quickly to get a project done. It's an important practical skill for their careers anyway.